#include<bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;
	string s;
	cin >> s;
	queue<char>x, d, ss;
	for(int i = 0; i < s.size(); i ++ ) {
		if(s[i] >= 'a' && s[i] <= 'z') {
			x.push(s[i]);
		} else if(s[i] >= 'A' && s[i] <= 'Z') {
			d.push(s[i]);
		} else {
			ss.push(s[i]);
		}
	}
	while(x.size()) {
		cout << x.front();
		x.pop();
	}
	while(ss.size()) {
		cout << ss.front();
		ss.pop();
	}
	while(d.size()) {
		cout << d.front();
		d.pop();
	}

	return 0;
}

